Means for ascertaining actual positioning of automobile wheels



Jan. 6, 1948. FE'LDS 2,434,205

MEANS FOR ASCERTAINING ACTUAL POSITIONING OF AUTOMOBILE WHEELS OriginalFiled June 15, 1942 2 Sheets-Sheet 1 INVENTOR.

01112123 FELDS TFORNSYS c. 1. FIELDS ,434,205

MEANS FOR ASCERTAINING ACTUAL POSITIONING OF AUTOMOBILE WHEELS Jan. 6,1948.

Original Filed June 15, 1942 2 Sheets-Sheet 2 FIGA.

ATTQ RN EYS Patented Jan. 6, 1948 MEANS FOR ASCERTAINING ACTUAL POSI-TIONING'OF AUTOMOBILE WHEELS Charles 1. Fields, Detroit, Mich, assignorto Arthur Jans, Detroit, Mich.

Original application June 15, 1942, Serial No. 447,080. Divided and thisapplication August 31, 1944, Serial No. 552,150

1 Claim. 1

This application is a division of my copending application Serial No.447,080, filed June 15, 1942, now Patent 2,357,463, granted September 5,1944.

This invention relates to means for ascertaining the actual positioningof automobile wheels, and particularly the steering wheels, withrelation to desired positioning thereof, including the toe-in positionof both wheels, and the steering wheel geometry, whereby the variationsfrom factory specifications, out of alignment conditions, and/or bentmembers, such as steering arms, can readily be found.

The principal object of my invention is provision of simple, rugged andpractical means for ascertaining the actual positioning of automobilewheels without complicated calculations.

A further object is to provide such means with easily read indicationswhereby changes from desired positionings can readily be checked by theoperators superior or viewed by the automobile owner.

Other objects and advantages will be apparent to those skilled in theart from the following description, wherein reference is made to theaccompanying drawings, illustrating a preferred embodiment of myinvention, and wherein similar reference numerals designate similarparts throughout the several views.

In the drawings:

Fig. 1 is a perspective view of a trammel bar with adjustable bracketsand traveling gauge mounted on one of such brackets for determiningtoe-in and toe-out positions of wheels.

Fig. 2 is a plan view showing the trammel bar and attached bracketscontacting the forward portions of the tires of front wheels, inposition for determining toe-in of wheel.

Fig. 3 is a view similar to Fig. 2 but with the trammel bar and bracketscontacting the tire portions in the rear of the front wheels.

Fig. 4 is a perspective view showing an angle gauge in cooperatingposition with the trammel bar for indicating the angle to which a frontwheel has been turned.

Fig. 5 is a plan view showing in diagram the steering geometry ofvehicle front wheels when one wheel is turned to a definite angle.

Referring now to the drawings, the numeral H designates the trammel bar,herein shown as a hollow rectangular member slidably mounted in a pairof supporting brackets l2 and 13 respectively, one of the brackets, asl2, having an upward extension terminating in a portion 12A bent atsubstantially right angles to the body portion of the bracket. Setscrews are provided for securing the brackets l2 and I3 in any adjustedposition relatively to the bar, and the supporting portions of thebrackets are such as to support the bar I I in a horizontal positionwhenever the brackets rest on a level surface. This arrangement enablesa quick check of the floor or other surface on which wheel tests are tobe made, and the trammel bar may be moved about to various positions onthe floor until a level portion is found, a carpenters spirit level orsimilar instrument being laid flat on the upper surface of the trammelbar while the level surface is being sought. Since it is necessary forthe front wheels of the vehicle being tested to be absolutely level inorder to secure correct caster and camber readings, this use of myimproved trammel bar will readily b appreciated.

Slidably mounted on the bar H is an adjustable bracket l l having anoffset portion extending in th same direction from the bar H as theoffset portion [2A of the bracket l2, and carrying an upright portion14B at the upper extremity of which is mounted a plate 140 having aportion formed as a journal for a traveling gauge bar MD. The plate I40carries a graduated scale ME over which a pointer MF attached to thegauge 14D moves to enable a ready reading of the movements of thetraveling gaug bar MD. A set screw MG is also provided in position tolock the guage bar MD in any desired adjusted position.

My improved trammel bar with its several brackets as above described, isparticularly useful in the determination of th toe-in positioning ofvehicle front wheels. In determining such toe-in, the trammel bar ispreferably first placed against th rear portions of the front wheels insubstantially the position shown in Fig. 3, with the adjacent surface ofthe trammel bar ll contacting the treads of both wheels and with thebracket l2 arranged with its extended portion 12A contacting the innerside of one tire substantially as shown. The traveling gauge bar MD isthen secured by the set screw MG with its pointer registering with zeroindication centrally of the graduated scale ME and the bracket i4 isthen slid along the bar ll until the face of the guage bar MD contactsthe outer side of the other tire.

The trammel bar with the brackets i2 and I4 secured by their set screwsin the adjusted positions as so determined is then removed from itsposition in the rear of the front wheels and placed into position at thefront of such front wheels, substantially as shown in Fig. 2. It will benoted 3 that the adjacent surface of the bar II is again brought intocontact with the treads of both wheels and the bracket arm I 2A intocontact with the inner side wall of one tire. Such positioning willimmediately determine whether or not the front wheels have any. toe-in,for if they have, the face of the traveling gaugeHID will beseparatedfrom the side wall of the opposite wheel, and to determine the amount ofsuch toe-in, it is only necessary to release the set screw MG and slidethe gauge bar MD towards the wheel until it contacts the outer side wallof the tire. The

amount of toe-in can then be read on; the indicating scale ME. Thesimplicity of this arrangement will immediately be apparent, and itsaccuracy is evidenced by the fact that straight line positions of thetrammel bar are assured by virtue of contacting the treads of bothwheels, while the tire sides are always contacted by the bracket arm IZAand gauge bar MD at the same height.

Todetermine'wheel wobble or bent wheel conditionsfthe points a-tfwhich'-the above measurements were made are marked on the Wheels, and then thecar is rolled, forwardione-half turn of the, wheels. Themeasurementsare:thenrepeated at the back and front of the front wheelsand'the'differencesdf" any, noted. It will also be-noted that the car'owner, or the mechanic's superior,- can readily check the readingatanyposition. 1 *My improved trammel bar is also useful inascertainingthe steering geometry of the-vehicles front wheels, or what is sometimesknown-as turn-; ing radius run-out; With this'in view,1I utilize thetrammel .bar with 'its innergface, contactin the treads:of the wheels asa base linegfrom which to accurately measure the angle'of wheel: turnoutwhen check readings are made; Such angle gauge is shown in Fig. 4 andcomprises a base plate I5 having an upstanding flange ISA at rightangles' to theplate for use as a guide in positioning the plate .forchecking purposes, An elon-. gated swinging member l6'is pivoted, as atIT, adjacent one corner of the plate I5 and carries adjacent its pivotedend a pointer I8 coo'perat-, ing with a radially marked indicating scaleI9 to show the angle of theswinging member I6 relatively to the baseplate. The Zero position on the scale is preferably when the ,member I6is at right angles to the flange I 5A of the ,base plate and graduationsextend on oppositesides of such zero position. A handle 20 is secured tothe mem-. ber I6 for convenient swinging movement as desired. r s Whenitis desired to ascertain the steering geometry of, the vehicles frontwheels, the trammel bar I I is arranged adjacent the fronts of thewheels then turned, say to the left, until the right-hand wheel is setat a angle. To ascertain this angle exactly, the trammel bar'is placedto contact with the fronts of the wheels, and the flange I5A of theangle gauge placed against the trammel ba substantially as shown in Fig.4. The-swinging member I6 is then moved into contact with the side wallof the tire and the angle of turning of the wheel may readily be read onthe scale I 9. After the right-hand wheel is accurately set at thedesired angle, say 15, as for example shown in Fig. 5, the position ofthe trammel bar is reversed and theangle gauge similarly placed tocontact the side wall of the left-hand wheel to read its angularposition. While steering geometry will vary with car models, the angleof the left-hand wheel in the above cited instance should read 18 plusor minus 1, and variations from this reading will indicate a bent radiusrod on theleft-hand wheel. Similarly, the steering geometry of theopposite wheel can be ascertained by then turning the wheels to theright until the left-hand wheel sets at a 15 angle as measured by theangle gauge. Then reverse the position of the trammel bar, and with theangle gauge, read the angle of the right-hand wheel. This should read 18plus or minus 1, and variations fromrthis reading indicate a bent radiusrod on the right-hand wheel.

The simplicity and ease of thus checking the steering geometry withfactory specifications will readilybe noted, and also that after a bentradius rod has been replaced; the front end can be rechecked quickly.and positively.

'I amaware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive; reference being had to the appendedclaim rather than to .the foregoing description to indicatethe scope Iclaim:

Means for ascertaining the actual positions of vehicle front wheelsincluding a horizontal trammel bar adapted to simultaneously contact thetreads of the tires of both front wheels at a substantial distance abovethe floor and carrying a pair of slidable brackets provided each with araised angular arm oifset toward the axles of said wheels, the offsetarm of one bracket directly engaging the side wall of the tire of onewheel, and a gauge having an indicating scale mounted on the offset armof the other bracket, said gauge including a slidable element adapted toengage the side wall of the tire of the other Wheel and carrying apointer movable over said scale.

7 CHARLES I. FIELDS.

of the invention.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,458,598 Spangenberg June 12,1923 1,822,983 Vanica Sept. 15, 1931 2,098,749 Johnston Nov. 9, 19372,159,084 Harrison May 23, 1939

